/**
 * @Author：ming
 * @Date：2023/10/2 9:39 PM
 * @Filename：Hj8
 */

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashSet;

/**
 * @author ming
 */
public class Hj10 {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String str ;
        while ((str=br.readLine())!=null){
            int len = str.length();
            HashSet<Character> set = new HashSet<>();
            for (int i = 0; i < len; i++) {
                set.add(str.charAt(i));
            }
            System.out.println(set.size());

        }
    }
}
